Properties of Visual Field Defects Around the Monocular Preferred Retinal Locus in Age-Related Macular Degeneration

To compare microperimetric sensitivity around the monocular preferred retinal locus (mPRL) in age-related macular degeneration (AMD) to normative data, and to describe the characteristics of visual field defects around the mPRL in AMD.

Participants with AMD (total n = 185) were either prospectively recruited (n = 135) or retrospectively reviewed from an existing database (n = 50). Participants underwent microperimetry using a test pattern (37 point, 5° radius) centered on their mPRL. Sensitivities were compared to normative data by spatial interpolation, and conventional perimetric indices were calculated. The location of the mPRL relative to the fovea and to visual field defects was also investigated.

Location of mPRL varied approximately 15° horizontally and vertically. Visual field loss within 5° of the mPRL was considerable in the majority of participants (median mean deviation -14.7 dB, interquartile range [IQR] -19.6 to -9.6 dB, median pattern standard deviation 7.1 dB [IQR 4.8-9.0 dB]). Over 95% of participants had mean total deviation worse than -2 dB across all tested locations and similarly within 1° of their mPRL. A common pattern of placing the mPRL just foveal to a region of normal pattern deviation was found in 78% of participants. Total deviation was outside normal limits in this region in 68%.

Despite altering fixation to improve vision, people with AMD exhibit considerable visual field loss at and around their mPRL. The location of the mPRL was typically just foveal to, but not within, a region of relatively normal sensitivity for the individual, suggesting that a combination of factors drives mPRL selection.